Phosphate mining in Banaba and Nauru
The economies of Banaba and Nauru have been almost wholly dependent on phosphate, which has led to environmental disaster on these islands, with 80% of the islands' surfaces having been strip-mined. The phosphate deposits were virtually exhausted by 2000, although some small-scale mining is still in progress on Nauru.
Source: Wikipedia — Phosphate mining in Banaba and Nauru (CC BY-SA 4.0)